This application claims priority under 35 U.S.C. xc2xa7xc2xa7119 and/or 365 to 00 08629 filed in France on Jul. 3, 2000; the entire content of which is hereby incorporated by reference.
1. Field of the Invention
The invention relates to a device for the assembly of an eyepiece-support arm on a fixed support attached to the lower unit of a sight system, such as the sighting head of a fire control system, on an aircraft.
The invention particularly relates to the sight means of a fire control system equipped on a rotary aircraft. However, it may be used on any other type of aircraft, without leaving the scope of the invention.
2. State of the Related Art
The sight means of a helicopter fire control system comprise a sighting head essentially located outside the helicopter cell. More specifically, the main part of the sighting head unit is generally located above the roof of the cell. A lower part of the sighting head unit, compact in size, is housed under the roof of the cell, in the cockpit. Said lower part forms a fixed support on which an eyepiece-support arm is mounted.
The eyepiece-support arm assembly device is designed to enable said arm to move between a position for use, wherein it projects downwards in the cockpit and a retracted position, wherein the arm is folded upwards against the roof of the aircraft. This device is also designed to enable locking of the eyepiece-support arm either in its position for use, or in its retracted position.
In addition, it is desirable to be able to disassemble the eyepiece-support arm, for example during a night flight of the helicopter. Indeed, in this case, the pilot frequently wears night vision binoculars which are liable to strike the arm and damage it.
As illustrated schematically in FIG. 1 of the appended figures, the devices currently used to assemble an eyepiece-support arm onto a fixed support attached to the lower unit of a helicopter fire control system sight system generally comprise a retention belt 01 circling the flanges formed on the arm and on the support, respectively.
The retention belt 01 is composed of two half-collars 02 and 03, wherein two adjacent ends are articulated together by a pivot 04. A toggle joint mechanism connects the other two ends of the half-collars 02 and 03. This mechanism comprises a lever 05 articulated on the second end of one 02 of the half-collars, a threaded rod 06 articulated on the lever 05 and a nut 07 normally fastened onto the threaded rod 06. Said rod is inserted into a slot 08 formed in the second end of the other half-collar 03, where it is held by a pin 09.
In such a device, precise setting is performed, by fastening the nut 07 to a varying degree on the threaded rod 06, so that the eyepiece-support arm is locked perfectly when the lever 05 is retracted against the half-collar 02 supporting it, while being free to rotate around the axis of the retention belt 01 when the lever 05 is switched downwards. The eyepiece-support arm can then be moved from its position for use to its idle position, or conversely.
In this known arrangement, the eyepiece-support arm can be disassembled by unfastening the nut 07 completely, in order to open the retention belt 01. Indeed, it is only when this operation has been carried out that the clearance between the belt and the flanges formed at the ends of the arm and the support is sufficient to release the arm.
The need to unfasten the nut 07 completely to disassemble the eyepiece-support arm represents a number of problems.
A first problem relates to the need to perform a new setting of the position of the nut on the threaded rod when the eyepiece-support arm is put back in place. Given the precision required for this setting, this operation may take some time, which represents a considerable drawback in the case of an emergency intervention.
Another problem relates to the fact that pilots frequently wear gloves. Therefore, the nut 07 unfastening operation is difficult to carry out. It may result in the loss of the nut, which may fall into the back of the cockpit, where it represents a foreign element liable to interfere with the numerous items of equipment located in the cockpit, such as the flight controls.
The invention specifically relates to an eyepiece-support arm assembly device, wherein the original design enables a person wearing gloves to disassemble the arm, when required, without modifying the setting of the retention belt in its locking status and eliminating any risk of a foreign body falling in the cockpit.
According to the invention, this result is obtained by means of an eyepiece-support arm assembly device on a fixed support attached to the lower unit of a sight system, on an aircraft, the device comprising flanges formed on the eyepiece-support arm and on the fixed support, respectively, and a retention belt capable of circling the flanges around a common axis, the retention belt integrating locking means capable of being set to a locking status, wherein the eyepiece-support arm is immobilised in relation to the fixed support and a setting status, wherein the eyepiece-support arm is capable of rotating around said common axis, in relation to the fixed support, characterised in that the locking means of the retention belt are also capable of being set to an eyepiece-support arm disassembly status, the status being changed between the locking status, setting status and disassembly status without any setting.
Due to the fact that the locking means of the retention belt are originally designed to be able to be set to an arm locking status, an arm setting status and an arm disassembly status, it becomes possible to disassemble the arm without modifying the setting making it possible to keep the arm in its locking status. In addition, said disassembly is performed without removing any parts, such that it may be performed by a person wearing gloves without any risk of a foreign body falling into the back of the cockpit.
According to a preferred embodiment of the invention, the retention belt comprises two half-collars wherein two adjacent ends are articulated together by a first pivot and two second adjacent ends connected by locking means.
In this case, the locking means preferentially comprise two levers, wherein each is articulated on the second end of a corresponding half-collar by a second pivot, and a connection rod articulated on each of the levers by a third pivot.
The second pivot and the third pivot of the first of the levers are then advantageously separated by a first distance such that switching of the first lever around the second pivot changes from the locking status to the setting status. Comparably, the second pivot and the third pivot of the second lever are advantageously separated by a second distance such that switching of the second lever around the second pivot changes from the locking status to the disassembly status, at least when the first lever is also switched. Preferentially, the second distance is greater than the first.
To enable the setting of the circumferential length of the blocking belt in its locking status, the connection rod integrates, preferentially, length setting means.
In this case, the length setting means advantageously comprise a double-threaded nut, fastened to two threaded rods articulated on levers by the third pivots.